The Johnson Sea Link carried a crew of four in two separate compartments. The aft compartment was originally designed for lockout diving, allowing two divers to be compressed to the ambient pressure of the ocean and leave the submersible to work underwater. The forward pilot's compartment was an acrylic sphere with a diameter of 5 feet (1.5 m), providing a panoramic underwater view for the pilot and an observer.[2][3]

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In 1973, during a seemingly routine dive off Key West, the Johnson Sea Link was trapped for over 24 hours in the wreckage of the destroyer USS Fred T. Berry, which had been sunk to create an artificial reef. Although the submersible was eventually recovered by the rescue vessel A.B. Wood II, two of the four occupants died of carbon dioxide poisoning: 31-year-old Edwin Clayton Link, the son of Edwin Link, and 51-year-old diver Albert Dennison Stover. The submersible's pilot, Archibald "Jock" Menzies, and ichthyologist Robert Meek survived.[4][5][6][7][8] Over the next two years, Edwin Link designed an unmanned Cabled Observation and Rescue Device (CORD) that could free a trapped submersible.[8]

In 1975, a second Johnson Sea Link was constructed by the Harbor Branch Oceanographic Institution.[3] In 1977, the JSLs were used to examine the wreckage of the ironcladCivil Warbattleship, USS Monitor.[3] They were also used in the effort to recover the wreckage of the Space Shuttle Challenger after its destruction in 1986. One of the JSLs discovered the solid rocket booster with the faulty seal which caused the shuttle to explode.[3] The submersible and its research program were featured in a Voice of Americastory in 2005. In 2010, Harbor Branch sold the Seward Johnson, the ship outfitted to deploy the JSLs, and laid off the submersibles' crew and support staff in July 2011, ending their operation.[9]